1. Field of the Invention
The present invention relates to a portable terminal device having keys and a control method of the same, and particularly to judgment of a depressed key among a plurality of depressed keys.
2. Description of the Related Art
In recent years, small-sized portable telephones have been commonly used. A small-sized portable telephone has many keys arranged in a limited space. These keys are small and arranged close to each other. For this reason, during key operations, a user of a portable telephone often depresses a desired key and other key(s) arranged in the vicinity of the desired key, at the same time.
In a portable telephone which is currently available, when a plurality of keys is simultaneously depressed, the key operation is disabled or the key depressed at the last is enabled.
Japanese Patent Laid-Open Publication No. Showa 58-105329 has disclosed a key selection method in which one of the above methods is selected. However, this method requires a user to depress keys repeatedly. In Japanese Patent Laid-Open Publication No. Heisei 7-13666, when two keys arranged next to each other are depressed at the same time, reference is made to patterns of a string of characters inputted before and after the depression. Based on a result of the reference, one of the keys is selected. However, with this method, a string of numbers such as a telephone number which has no meaning cannot be processed. Japanese Patent Laid-Open Publication No. 2000-66817 has disclosed a touch panel provided with a learning function. A learning unit of the touch panel changes a key input receiving range based on corrected input data. However, this method cannot be applied to a keyboard having keys.